Traffic control signal



Sept. 6, 1938. P. B. RENsHAw 2,129,445

' TRAFFIC CONTROL SIGNAL Filed June-22, 1953 4 Sheets-Sheet 1 INVENTOR Piper BA/LfV Paw/MW BY dar A TTORNE Y5 4 Sheets-Sheet 2 Sept. 6, 1938. P. B. RENSHAW TRAFFIC CONTROL SIGNAL Filed June 22, 1933 B. P 35 ,741 F/aQ Sept. 6, 1938. P. B. RENSHAW TRAFFIC CONTROL SIGNAL Filed June 22, 1953 4 Sheets-Sheet 3 m WW WW Vm T Q N ha g B Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE TRAFFIC CONTROL SIGNAL don, England Application June 22,

1933, Serial No. 677,029

In Great Britain June 30, 1932 10 Claims.

The present invention relates to traffic control signals for use at road crossings or the like and is more particularly concerned with a progressive type trafiic control system by means of which a number of controllers located at successive crossings on a main road may be regulated from a master timer in a certain phase relationship to each other, so that if the average speed of the traffic is known it is possible to time the control signals so as to ensure a substantially continuous flow of traific along the main road. Systems of this type have been found to give good results in use but their operation is not particularly flexible in that they require the controllers to be individually set as regards their time periods in the cycle, and a further disadvantage is the danger that all controllers will cease to function in the event of a breakdown at the master timer.

From the point of view of the traffic engineer in charge of the system, individual setting of the controller is undesirable and definitely precludes quick adjustment of the time cycle since each controller requires a personal Visit. By far the more satisfactory arrangement is for complete control to be exercised from some master point where the necessary traflic data and timing charts for the whole system are readily available. It is also desirable that service shall be maintained even if the master timer fails and although this latter event is extremely improbable, the possibility of a complete stoppage of all controllers along an important route should preferably be eliminated. Accordingly the object of the present invention is to provide an improved system of the type described which obviates the shortcomings mentioned and provides in a particularly reliable manner the improvements mentioned.

According to one feature of the invention in a progressive system of traffic control the individual controllers are operated by impulses transmitted thereto at different times from a master timer so that their phase relationship may be altered at the master timer.

According to another feature of the invention in a progressive system of traffic control in the event of a complete failure of the master timer the individual controllers which are nor- 'mally regulated thereby continue to function owing to the provision of independent timing apparatus.

The invention will be better understood from the following description of one me h d, Q; @84

rying it into effect, reference being had to the accompanying drawings, in which Figs. 1 and 2 show by way of example a master timer arranged to regulate three controllers of which the circuit connections for one areshown in detail, Fig. 3 shows one form of individual traffic actuated controller and system which may be controlled by the master controller, and illustrates in more detail the embodiment shown in brief in the rectangle of heavy dash lines in Figure 2; Fig. 4 illustrates another form of individual trafi'lc actuated controller, in which traflic actuating devices may be employed in each road, and. illustrates an arrangement whereby certain maximum periods of right of way may be controlled by the master timer.

It should be explained generally that the system comprises a master timer from which separate pairs of conductors radiate to each controller for the purpose of regulating their time periods in relation. to each other. The controllers may be conveniently of the general type disclosed in British specification No. 355,741 but for the purpose of the illustration in Figure 1 and Figure 2 may be arranged to operate at fixed time periods independent of the traflic flow, that is to say, there is no question of extending their normal period as a result of a continuous flow of traffic passing over a road contact or the like. These controllers will be set to operate at rather long periods, considerably in excess of that required in the progressive system, but the periods will be curtailed by the right amount upon the reception of socalled light and heavy pulses over the control leads from the master timer.

Referring now to the circuit shown, the system is arranged for operation from A. C. mains and suitable rectifying arrangements are provided for obtaining direct current to operate the relays and neon lamps. In the drawing the alternating current mains designated I and II are shown incoming from the left hand side of Fig. 1 and for the operation of the master timer a tapping is made from these leads by way of the fuses FUS and main switches MNS to the primary winding of the transformer XFR. This transformer is provided with three secondary windings, two of which connect with the thermionic valve amplifier VLV which supplies direct current of the order of 400 volts to the terminals designated and in a circle, for the purpose of flashing the neon lamp N. The third winding on the secondary side of the transformd1 XFR connects with the full wave metal rectifier bridge MRA which supplies direct current of the order of volts to the terminal points marked and in a square, for the purpose of operating the relay F and the driving magnet DSM. Essentially the master timer comprises a rotary step-by-step switch DST of the type used in automatic telephone systems which may be completely immersed in .oil and. arranged to be operated step by step from a neon lamp impulser, the speed of which may be altered, by. varying the setting of the resistance switch 12 connected in series with the condenser QBQ' As regards the automatic stepping. circuit, 1

should be explained that when the neon lamp N flashes as the result of the.charging. of the condenser QB to the required voltage, relay E is operated in series therewith, thereby at armature el operating relay F, and at armature,- e2 connect:

ing negative potential to the wipers "of the switch DST. Relay F on operating, at armatureflcome pletes the circuit for the driving magnetDSM, at armature ft supplements the connection-to the wipers of the-switch DST, at armature f3 shunts the neon lamp N and relay'E by way of resistance- YB, andat armature -,f4-flashes the master fail alarm lamp MFA. .Relay E thereupon releases andupon the release of relay F after its slow period due-to the copper slug on its core, the driving magnet is de-energized to advance the wipers on to the next set of bank contacts. This action continues automatically so long as the system is in service; One bank-and wiper of the switch DST'is'allotte'd to each controller to be regulated and the control leads extend from the appropriate contacts in the associated bank. Bank la connects with controller No. I- of whichonly the regulating relays have been shown in the dotted rectangle; this controller may be located adjacent to the master timer. -Bank 20. connects with controller No. 2 shown in Fig. 2, and bank 3a connects with controller No. 3; whichis not shown as it is: assumed to be identical with controller No. 2.

In the drawings each control lead is shown as making. two connections with its associated bank,

one of which is directand the other extends by way of'a resistance. Consequently as the switch rotates so-called light and'heavy pulses aredelivered over the control leads to the respective controllers in turn.

The control. leads may comprise light gauge wires, for example, telephone lines, and terminate inthe controllers on a pair. of relays B and C shown in Fig. 2 connect'edsin series one of which is marginal.

Asa result of the operation of one or both of these relays fromthe light and heavy pulses the signallights of the controller. are regulated; accordingly. I

Inthis particular example the complete cycle time ofthe system is represented"by 25 steps of the rotary'switch DST in themaster. tim'er. Each stepof the switch therefore rep-resents 4% of the total cycle. time so that by varying. the connection of the control leads to: the banks the phase relationshipbetween the difierentsets of control signals may-xbeadjusted to a very fine degree.

Each ofi't'hecontrollers, which are. all identical, comprises: essentially a battery. of cams mounted on a'commonashaft" and arranged to close contact pulsedatpredeterminedtime.periods from aineo'n' lamp .timingdevice,comprising the. lamp IN and .irnthe figure by a black circle or a bar.

"If it is assumed with regard to controller No. 2,

. that thecamshaft is in its first position, cam contacts Ci, C9. and C22 will be operated, thereby lighting the green signal lamps GNS for the northsouthroad, and the red signal lamps REW for the east-west road,-while at the same time over cam contacts Cl, a circuit is complete from the valve rectifier I VLV by way of a tapping on the common resistance I3 for charging the condenser -QA. 'Afterthe initial period of for example, 10

seconds has elapsed, the condenser QA will be charged sufficiently to cause the'neon lamp IN to flash over, thereby operating relay A which at armature al energizes the solenoid S which advances thecam shaft into its second position. In this position, as will be evident from the chart, the signal l'am-ps already lit are maintained and over cam springs C2 and the adjusting switch shown a charging circuit is again completed for the condenser. Four such adjusting switches are shown in the drawings and it should be explained that the terminals of these switches connect with suitable tapping points on the common resistance l3. To meet the requirements of the invention the resistance now connected in circuit must be very high to ensure that the condenser charges slowly, and for this reason the adjusting switch in question is preferably'turned round into its extreme position where it will be understood that it connects with the end of the common-resistance shown.

During progressive working this particular timing circuit will have practically no effect on the operation of the controller since with the normal operation of the master timer a light pulse is de livered over the control leads before it becomes operative. As already explained this light pulse is obtained by including a high resistance in the pulse leads at the banks of the master timer, and as a result relay B only is operated in the controller, thereupon at its armature bl in conjunction with the cam contacts C1 completing low resistance charging'circuit for the condenser QA. Almost" immediately therefore the neon lamp IN flashes and causes the controller to step to position 3. Non-inductive resistances are connected across the control leads as shown in order to guard against. false operation owing to surges and inductive discharges.

In accordance with the change of the cam contacts, the green lights for the north-south road are now replaced with amber lights ANS, and over cam contacts C3 and the adjustable resistance switch a circuit is completed for the condenser QA to control the duration of the amber signal. With this arrangement although the phase of the amber signal may be changed when an adjustment is made in the cycle at'the master timer, its'actual duration remains constant since it is determined by the setting of the local adjusting switches and is not influenced by the relays connected to the control leads.

In case it should be desired to show the amber signal simultaneously to both roads, as is the requirement of certain administrations, this may be achieved by bridging the amber circuits by means of the strap and switch [4 shown in the drawings After the duration of the amber warning period the solenoid S again operates to step the cam shaft to position 4 and the control signals are then completely reversed while over cam springs 04 a charging circuit is completed for the condenser QA which provides an initial timing period of 10 seconds for the east-west road. When this period has elapsed, the solenoid S steps the cam shaft to position 5 and although the signals previously showing are retained, the charging circuit for the condenser QA is completed by way of the very high resistance as a result of the adjusting switch associated with cam contacts C5 being turned into an extreme position.

Here again this second comparatively long time period has practically no effect upon the controller during normal progressive operation since a heavy pulse will be received from the master timer meanwhile, which results in the operation of the timing switch, and providing the master timer is functioning correctly, the time periods of their stop and go signals will be directly regulated therefrom.

If, however, for any reason the master timer should fail in such a manner that no further impulses are delivered over the control leads, the individual controllers will continue to function satisfactorily at somewhat longer time intervals as a result of the charging circuits completed over the cam contacts C2 and C5. Moreover, in case a particular line fault on the control conductors should maintain operated one or both of the signal relays at the controller, the latter will continue to function at somewhat shorter time intervals as determined by the initial timing circuit completed over cam contacts Cl and C4.

In addition to the normal operation of the system and the necessary safeguards against failure, it is also possible to provide special features such as for example causing all controllers to show a red signal to all approaches thereby effecting a complete hold up of the traffic. This condition may be brought about instantaneously from the master timer by the operation of the 'manual switch which closes the contact marked ARS in the drawings, thereby connecting potential to a common wire [5 extending to all controllers which results in the operation of a relay AR in each. Relay AR, at armature arl disconnects the operating circuit for the controller which is thus brought to rest in the position to which it is set, at armature arZ opens the circuit of the green and amber signal lamps and at armature m3 bridges the circuit of the red signal lamps so that both sets are lighted. It will be appreciated from a consideration of the chart that in all positions of the controller one or other of the red signals will be showing and therefore the connection described will be effective no matter in what position the controller is brought to rest.

For the purpose of switching the controllers on and off a further common wire I6 is provided which connects with the switch contact CSS3 at the master point and a relay CS in each controller. The operation of the switch CSS disconnects the master timer insofar as its control function is concerned by opening the circuit to the valve rectifier VLV at springs CSSI and CSSZ,

and at springs 'CSS3 connects potential to the common lead Hi to operate a relay CS in all controllers, which thereupon at armatures csl disconnect the respective controllers from the alternating current mains. This method of control is preferred to the alternative, whereby the relay is operated to connect up the controller since a failure at the master timer might then result in the individual controllers becoming disconnected.

Arrangements are also provided by means of a special manual switch at each controller whereby the all red feature may be brought into action at that particular point only. When this manual key is operated, the springs ABS! and ARSZ are actuated, thereby disconnecting the circuit for the green and amber signal lamps and also connecting together the red signal lamps so that both sets show simultaneously regardless of the position of the controller.

In case it should become necessary under certain circumstances for a particular controller to be operated manually, the required circuit changes are brought about by the operation of a further key which actuates the springs MAN! and MANZ to disconnect thetiming circuit of the controller and also connects the solenoid S in circuit with a push button PB. The operation of the push button by the officer in charge causes the controller to step through its cycle and any desired time periods may be allowed.

As already explained, a supervisory lamp MFA is provided which is located in a conspicuous position at the master timer and arranged to flash in synchronism with the stepping switch. Failure of the switch to step due to some mechanical trouble will therefore be evident by the failure of the supervisory lamp to light and the traffic engineer is thus acquainted of the fault. An indication is also given of the blowing of the main fuse or similar trouble in which event the lamp is extinguished.

In case the master'timer. is switched on at a time when certain of the controllers are out of phase, the correct phase setting between each will be restored when the stepping switch in the master timer has made one complete revolution.

The application of the progressive system of control to an existing system of road-pad-operated controllers is also contemplated according to the invention. In this connection it will be realized that when a system of road-pad-operated controllers for example of the type described in British specification No. 356,102 previously referred to, is working under heavy traffic conditions, the occurrence of the maximum timing periodwill be the rule rather than the exception, and under these circumstances the controllers become in efiect fixed time controllers working on their maximum timing limits. In the application of the invention to such systems it is proposed to associate each controller with a master timer in much the same manner as that disclosed in the accompanying drawings and arranged so that control will only be exercised therefrom when the controller attains its maximum timing limit. For this purpose it is proposed to so modify the existing controllers that when the maximum timing limit is reached the signals will not immediately change but rather the circuits will be put into a condition such as to be responsive to the regulating pulses from the master timer. This is best achieved by placing the maximum timing circuit in each controller under the control of the relay which is operated from the master timer. With this arrangement when a number of controllers attain their maximum timinglimit they will be-temporarily held'in this condition and thereupon released progressively under the control of the relays operated fro-m the master timer. It will be understood however, that the master timer and associated control relays are operated continuously but their operation is only effective when the controllers in question are working on their maximum timing limits.

The actual circuits might be similar'to those disclosed in British specification No. 355,741 which shows a traffic control arrangement of generally similar type provided with neon lamp timers. Referring now to Figurev 3 illustrating an enlargement of the diagram outlined in heavy dash lines in Figure 2, the operation of this embodiment of a road pad operated controller will be described. In this illustration road pads or traffic detectors are omitted from the main street designated as A and provided only in the cross street designated as B. The right of way is accorded to cross street B upon actuation of a traffic detector in this street and after a period of right of way in this street which varies between a minimum and a maximum depending upon the frequency of further traffic actuation in this street the right of way'is automatically transferred to the main street A. It is accorded to this street for a minimum period before it can be transferred again to street B, in response to actuation in the latter street. Timing means is also provided so that in the event of absence of actuation on street B for a relatively long period the right of way may be automatically transferred tothe cross street to care for pedestrian trafiic or any cross traffic which-may have failed to actuate the road pad. The apparatus can readily be arranged to disconnect this timing means so that right of way will remain continuously on street A until actuation by traffic on street B.

The construction of the apparatus illustrated in Fig. 3 is similar to that illustrated as a part of the individual controller in Figure 2 particularly in the arrangement of the cam shaft and means for operating the cam shaft and in the use of a condenser and discharge tube timing arrangement. In Figure 3 it will be noticed that there are 16 cams and 56'II represent contacts operated by these cams.

The scheme of representation shown under numeral 12 is as follows: In one position, for example, A, contacts 51, 60, 62, 63 and 61 are closed. If magnet. 29. is now energized and de-energized the cams will be notched or shifted to position B. Contacts 62 and 63 remain closed. Contacts 51, 60 and 61 are now open, but contacts-58, GI and 69 are closed. The operation is similar as the cams are notched successively to positions C, D, E and F. In this figure the notching magnet 29 is again indicated and whenever energized, operates the 3 switch members 93, 94, and 95 which represent schematically the 3 circuit closers operated by the plunger of solenoid 29. Member 93 is the one which is made as soon as the motion of the plunger starts and 94v and 95 are the two which are made at the end of the motion of the plunger upon energization of the solenoid. Elements 96 and 91 represent relays, and whenever either relay is energized, magnet 29 is energized because current flows from wire 98 through wire 3|, magnet 29, wire 30, and, in case relay 91 was energized, through armature I00, contact IOI, wire I02 and wire 99 and, in case relay 96 was ener- V gized through armature I03, contact, I04, wire I02 andwire 99., Wires 98 and 99 are connected to a source of. power.

As will appear later, when all traffic has ceased on street B, the apparatus will eventually come to rest in position F. In this position contact 56 is closed lighting the A street green signal, and contact 59 is closed lighting the B street red signal. Thus, the right of way is being given to thehighway and vehicles may proceed on that street. At the same time, contact 65 is closed allowing current to flow from wire 98 through contact 65, resistance I05, wire I06, wire I01, wire I08, condenser I09 and wire 99, and the voltage of condenser begins to build up at a rate determined by the value of resistance I05. Assume that this resistance is adjusted so that condenser I09 is charged up to the critical voltage of tube H in thirty seconds. However, even though condenser I09 reaches the critical voltage of tube H0, tube H0 doesnot become conducting because its discharge circuit is open at contact 93 and in addition is open at armature III and contact II2. In applying applicants invention to this apparatus the discharge circuit also includes the contacts c2 of the master control relay C and is held open until contacts 02 close. Thus, the system remains inactive and right of way continues to be shown to the highway. i

If a vehicle approaches on the cross street operating one of the vehicle actuated control devices located there, the circuit between wires I0 and II willbe closed momentarily allowing current to flow from wire 98 through wire I I3, relay II4, circuit II and I0, wire H and wire 99. This would effect only a momentary closure of relay H4 were it not for the locking circuit consisting of contact IIS, armature II'I, wire II8, contact 62, (contact 62 being made in position F), and wire II9, this locking circuit being made when relay II4 operates. When relay II4 operates, it closes contact between armature II I and contact I I2 partially, completing the circuit shunting condenser I09 through wire I20, so that as soon as contacts 02 of the master control relay have closed the circuit through the tube H0 is completed. Tube IIO becomes conducting and the energy stored in condenser I09 discharges through relay 9'! operating it momentarily. This closes contact between armature I00 and contact IOI, energizing magnet 29 which in turn rocks the notching mechanism. As soon as the coreof the solenoid has been fully attracted, circuit between wires 89. and 90 is made which shunts resistance I2I directly across the terminals of condenser I09. Resistance I2I is of a very low value, its only purpose being to prevent arcing,

when switching mechanism 94 closes. This allows any energy remaining in condenser I 09 to be dissipated in resistance I2I, tube IIO becomes non-conducting, the energizing circuit of relay 9! is consequently broken, armature I00 separates from contact IM and magnet 29 becomes de-energized. This allows the notching mechanism to return to its normal position, and in so doing, to shift or notch the cams from position F to position A.

In position A, contact 51 is closed, lighting the A street yellow signal, and contact 60 is closed, lighting the B street yellow signal. At the same time contact 93 is closed insuring that the discharge circuit of condenser I09 through the tube IIO shall remain closed regardless of subsequent action to relay II4. At the same time contact 61 is closed allowing current to flow from wire 98. through contact 61, resistance I22, wire I23,

wire I24, wire I25, con denser l26" and wire 99, and in a similar manner the voltage of condenser I26 begins to build up ata rate determined by the value of resistance I22. Assume that the period required is 2 seconds. At the end of two seconds, condenser I26 reaches'the critical voltage of tube I 21 and the energy stored in condenser I 26 discharges through tube I2'I and relay 96. Relay 96 operates, closing circuit between armature I03 and contact I04, energizing magnet 29, which in turn rocks the notching mechanism. When the solenoid core has moved to its extreme energized position, switching device 95 closes circuit between wires SH and 92, placing resistance I20 directly across the terminals of condenser I26. Resistancev I20 is similar to resistance I2I' and performs the same function for condenser I26 that resistance I2I performs for condenser I09. The remaining energy of condenser I26 being dissipated in resistance I28, relay 96 becomes de-energized, de-energizing magnet 29 which allows the notching mechanism to again move forward the cams, which shift from position A to position B. In position B, contact 58 is closed lighting the A street red signal, and contact 6I is closed lighting the B street green signal. The right of way is now being given ,to B street and the vehicle which approached there may cross. In position B, contact 69 is closed and current flows into condenser I26 through resistance I29, and condenser I26 reaches the critical voltage of tube I2'Iin 3 seconds. At this moment tube I2'I becomes again conducting and the notching operation proceeds in the very same manner previously described, advancing the cams from position B to position C. In moving from position B to position C, there is no change in the signal lights, contact 58 and 6| remaining closed. Contact 62, however, is open, which breaks the locking circuit of relay II4 which drops to its de-energized position. In addition, contact 'II is closed, and since relay I I4 is de-energized, current flows from wire 98 through resistance I30, contact I3I, armature I32, contact II, wires I23, I24 and I25, condenser I26 and wire 99, and similarly the voltage of condenser I 26 begins to build up at a rate determined by resistance I30. Assume that this resistance is set so that condenser I26 builds up to the critical voltage of tube I21 in '7 seconds. Assuming that no further cars approach on the cross street, then after! seconds, condenser I26 will discharge through tube I 21, performing the very same steps of the notching operation described'previously. This notches the cams from position C to position D.

In position D, contacts 51 and 60 are again made, lighting both the A and B street yellow lights. In addition, contact 68 is made which closes the charging circuit of condenser I26 through resistance I33. Assuming that resistance I33 is set to charge condenser I26 up to the critical voltage of tube I2I in 2 seconds, then condenser I26 will discharge after 2 .seconds and the notching operation will proceed again as described previously, shifting the cams from position D to position E. 1

In this position, contacts 56 and 59 are made, lighting the A street green signal and B street red signal, and the right of way has returned to the highway. At the same time contact I is made which charges condenser I26 through resistance I34 as previously described. Assume that the period timed, as determined by the setting of resistance I34, is 5 seconds. Then after 5 seconds, the advancing operation will again proceed, as'previously described, and the cams will be moved from position E to position F. We have reached the'condition described at the beginning, and charging of condenser I09 starts, contact-65 being made. But after condenser I09 has reached the critical voltage of tube IIO, it does not discharge through said tube because the discharge circuit is open, as described previously.

I have thus described theoperation of the device assuming that only one car approached on the cross street. It will be noticed that after right of way has been showing on the highway for a certain length of time, right of way is immediately'callable to the cross street, should a; vehicle approach there. But if a vehicle should approach on the crossstreet at any time after the cross streethaslost right of way, and before right'of Way has been given to the highway fora certain lengthof time, relay 4 will operate and lock in, closing the discharge circuit of condenser I09, but,-no"discharging of condenser I09 can take place iuntilit has been charged to the critical voltage of tube H0, and this cannot take place untilright of way has been showing on the highway for a certain length of time.

If right of way-has been transferred to the cross streetin response to a vehicle approaching there, and a second 'vehicle approaches on the cross street before the end of the '7 second period which is timed in position C, relay I I4 will operate, causing armature I32 to touch contact I35, which shunts resistance I36 across the terminals of condenser I26, atthe same time interrupting the charging circuit of condenser I26. It will be noticed that the length of time circuit between wires I0 and II remains closed depends entirely upon the length of time the wheel of the vehicle I is on ramp 5. And this again depends entirely upon the speed of the vehicle. The slower the vehicle is travelling, the longer is this length of time, and the faster the vehicle is travelling, the shorter is this length of time. Consequently, adjustableresistance I36 is shunted across the terminals of condenser I26 for a period of time dependent entirely upon the speed of the vehicle operating relay II4. If the vehicle is moving slowly, this time will be longer and practically all the energy stored in condenser I26 will be dissipated in resistance I36, and thus when the energizing circuit is re-established, charging of condenser I26 will start with practically no stored energy in the condenser, and the time required to charge it up to the critical voltage of tube I2'I will be practically 7 seconds. Ifthe vehicle is travelling fast, the time of discharge, and consequently the amount of discharge will be small. Thus, when the energizing circuit is re-established, charging of condenser I26 will start with some remaining stored energy, and the period timed will'be the period necessary to charge condenser. 126 from the voltage existing at the moment to the critical voltage of tube I2I. The time period will be shorter by the amount of ti'methat' would have been'necessary to charge condenser I26 from zero voltage tothe voltage to which it had been reset. Thus it appears that the amount of reset depends upon the length of time the energizing circuit is interrupted.

As soon as traflic ceases to approach on B street, condenser I26 will discharge through tube I2I, notching or advancingthe cams to position D, and from then on the operation is asdescribed above.

Should vehicles approach continuously on B street, continually resetting condenser I26, right 75' ofpway would remain indefinitely-on the cross street to the disadvantage-of the highw'ay unless some limitation is-imposed upon the length of time the cross street may retain right of way. It

will be noticed that in position C, contact is closed which allows charging current to flow into condenser I09 through resistance I31. Assume that resistance I31 isso adjusted that condenser I09 will reach the critical voltage of tube 0m 20 seconds. This condenser is notresetby approaching vehicles, and if traffic'continues at the end of 20 seconds, condenser I09 will discharge through'tube I I0,operating relay 9'! which energizes magnet 29, and the mechanism, notches to position D as described previously, provided contacts 02, forming a part-of the discharge circuit through the tube, are closed. It will be seen that themaster timer through relayC is able to controlthe transfer of right of wayfrom'street B by-the maximum timer. Thediiference is that relay 9! also operates armature I38 which touches contact I39 which allows current to-fiow through relay H4, operating it. The energizing circuit made at armature I38 is only-momentary and relay I I4 would notremainenergized, (its locking circuit being broken at contact 62) were it not'for contact device 9-3 which is made as soon as notching mechanism 26 begins-to move. This completes circuit between wires I8 and I9 whichprovides a temporary locking circuit. Contact'62 is made in position D and as a matter of fact, is made slightly before the notching mechanism has completed its clockwise notching movement, and is so *adjusted that contact62 is made just before circuit betweenwires 18' and His broken, maintaining relay H4 in an energized position. Thus, while some vehicles have lost right of Way before they have had suflicient time to cross the intersection, the system remains in such'a condition that without requiring anyaddition'al actuation of the B street vehicle actuated device, rightof way will'revert to B street at-the'end of the highway right of way period.

It will be noticed that right of way is being given to -B street in position B although the resettable timer has not begun to operate. This period, in this case -3 seconds, is the period provided to allow one or more'vehicles'which may be waiting on B street to get into motion, and presumably the last of such waiting vehiclesis actually-in motion when the mechanism notches the cams to position C. I

If no vehicles are waiting on B street, right of way will be given to the highway and may remain there indefinitely, thuspreventing'pedestrians fro-m crossing the highway. It is sometimes desirable to provide-a system-which will occasionally shift right of way'to the cross street even though there are no vehicles waiting thereon, stopping the highway traffic and allowing pedestrians tocross thehighway. Thls'may be accomplished through contact Eli-which is made in position F. This charges condenser I26 through resistance I39, and this resistance is adjusted so that condenser I26 ischarge'd to the critical voltage'of tube I-2'I in Zminutes. "This notches the cams to position A-andfrom then on they automatically advancethemselves through the succeeding positions. Ofcourse, should vehicles approach while cams are in position C, they will reset condenser I26, asdescribed previously. But if no vehicles at'all-a-pproach right of way will shortly be returned to the highway and highway traffic may proceed.

It will be obvious that this "automatic transfer of right of way to the B street in the absence of trafiicactuation can be disconnected by means of a switch which may conveniently be placed in the timing circuit between cam contacts '66 and timing resistance I39. 7

In describing the operation of the system, I have shown the device as exhibiting the signal lights in the usual sequence, namely, green, yellow, red, yellow, green. It frequently is desirable to omit the showing of yellow when the shift is from red to'green, and continue to show a red light while a yellow light is being given to the street which is losing right of Way. This can be easily accomplished by providing that the cam under contact 51 operates the contact only in position A, that the cam under contact 58, operates the contact through position B, C, and D, that the cam under contact 59 operates the contact through positions E, F, and A, and that'the cam under contact '60 operates the contact in position D only. Obviously by'su'itable arrangement of the cams any other desiredsignal sequence'may be obtained.

For the purpose of manual-operation a switch I40 is opened, thus disconnecting the timing mechanism from the lights. The lights may be operated manually by simply pressing push button III, which, uponeach functioning, energizes magnet'29 thus advancing the cams through their cycle and in so doing transfers right of way from one-vehiclelane to the other.

Referring further to Figure 3 and the condensed illustration shown in Figure 2 themaximum'timing circuit in this case is that associated with'the'condenser I09 and the'discharge circuit therefor-has 'to be closed over contacts '63 or 'arma'tureII I. In the arrangement contemplated according to the invention this discharge circuit would only be completed by the relay responsive to the controlling pulses from the master timer.

Asillustrated this control may be providedfor by omitting'the direct connection'between relay 91' and'armature III which would be employed where this controller is used as an isolated system independent of any master control and by running this circuit through'the contacts 02 of the "master -control relay C. It will be'noted as described above that the discharge tube 'I'I0'and the relay-'91 are a part of the timing 'circuit'serV- ingas a maximum timer in position C of the cams through the 'camcontact 64 and also serving as a minimumtimer on street A'in positioniF of'the camsthroug'h the cam contact 65. Thus it will beseenthatthe operation of the maximum'timer in position C on the cross street will be controlled by the master control relay C and it will alsocbe seenthat the'completion of the time period to permit transfer of right of way to the cross street in response to cross street actuation willin'positionF' also'be under the control ofmaster control relay C, thuspermittin'g the master timer to control the transfer of right of way to the cross street in response'to actuation and also to control the retransfer' of'right of way to the main street in theevent of traflic on the cross street being sufficiently heavy to produce extension of the cross street rightof way period up to the maximum.

Referring now to Figure 4 the presentinvention is'shown -applied to "govern operation of a traflic signal controller of the full-actuated type, having: detectors in'both main and cross streets. Such'a'full-actuated controller is disclosed in British Patent 356,102, and application of the invention to this type controller provides for controlling the instant of releaseof right of way from each street if the right of way is prolonged up to a maximum.

In Figure 4 there is represented timer I39 of British Patent 356,102 and when current is applied at its terminals E, E it times the maximum duration of right of way for traffic on one of two intersecting streets, for example, A street, causing release of right of way from A street by the separation of armature 51 from contact 56 at the end of the maximum time period. Timer I3! is the corresponding maximum timer for the other or B street controlling release of right of way from B street by its armature 86 and contact 81. Each of these timers serves as a time delay relay, the time delay period being determined by a condenser-gas discharge tube timing unit. When current is applied to terminals E, E of timer I39, relay I1 is energized closing armature 2| against contact 2|] to complete a charging circuit for condenser 24 over high resistance I 9. When condenser 24 has acquired a voltage above the conducting potential of gas discharge tube 26, and assuming the contact 02 closed, a circuit parallelling condenser 24 is completed through tube 26 and relay 2'! is energized by the charge stored in the condenser. Relay 21 looks in via its contacts 30 and its armature 51 breaks at contact 56 a control circuit for causing transfer of right of Way. When current is disconnected from terminals E, E relay I! is deenergized, at contact 20 the condenser charging circuit is interrupted, and at contact 32 a circuit is completed via low resistance 33 to completely discharge the condenser in preparation for timing the next interval.

In accordance with the present invention as shown in Figure 4, the circuit through tube 24 and relay 2'! parallelling the condnser is not completed unless or until relay C is energized by the master timer to close its contacts 02. Thus, after the condenser charging period of the maximum timer I39 is completed, the instant at which right of way may be released from A street by operation of relay 2'! to separate contacts 5651 is determined by the time of operation of relay C by the master timer. Similarly, termination of the B street right of way by maximum timer I31 is governed by the time of operation of relay B. In this way at one or more full-actuated controllers the transfer of right of way at the end of the maximum period may be controlled by a master timer in accordance with the invention.

The term controller is used herein broadly to designate the mechanism located at the individual intersection for .operating the signals through their cycle of right of way indications and in the present embodiment this controller includes a timing device for determining the time periods of display of the difierent right of Way and cautionary change indications in. the cycle, but which timing device is normally superseded in effect by an external timer in determining the period of the right of way indications in certain parts of the cycle. This external timer is designated herein as timer or master timing means for convenience in distinguishing from the individual or local controller and as representative of its functions of maintaining the cycle of the individual local controllers in predetermined time relation. The master timer it will be observed includes a timing device providing closely spaced periodic impulses, and a cyclic switching device having distributing units for providing impulses at different preselected points in the cycle to the individual controllers, all the units being operated master in unison step by step by the impulses of the timing device. In this respect the master timer acts as a common timing means for the several individual local controllers. In the embodiment shown in Fig. 3 the controller is operated by its timing device subject to modification of the timing by trafiic actuated means.

It will be understood that various changes in construction and rearrangement of the parts of my system might be made without departing from the spirit of my invention as defined in the claims.

I claim: I

l. A signalling system for interfering lanes at a crossing including signals to accord and interrupt right of way over said lanes, means, when operative, operating to cyclically accord right of way to the respective lanes for periods of time for the control of traffic, said means including a device for predetermining the time of the beginning and ending of the said periods, a control station, means including timing mechanism at said station for sending spaced impulses spaced cyclically, the said second cyclic operation being of less duration than the first cyclic operation, and means responsive to said impulses to affect said device to shorten said periods by advancing the time of ending of said periods.

2. A signalling system for an intersection of trafiic lanes, including signals to accord and interrupt right of way in said lanes, controller means operating to cyclically accord right of way alternately to the respective lanes, said means including a timing device for determining the time periods of said accord of right of way, a control station, means including timing mechanism at said station for sending cyclically spaced im-- pulses, the said second cyclic operation being of less duration than the first cyclic operation, and means in said controller responsive to said impulses to afiect said device to shorten said periods at a certain point in the cycle of the first cyclic operation to normally control said first cyclic operation.

3. In a trafiic control system for a plurality of intersections of trafiic lanes having at each intersection a signal and controller operating the same through a cycle for according right of way successively to such lanes at such intersection, a central master timer normally operating through a shorter time cycle than the cycle of said controller for controlling the phase relation between such controllers and maintaining them in step with the master time cycle, said master timer comprising a periodic impulse generator, a step-by-step rotary switch having a plurality of contact positions and connected to be stepped periodically and cyclically through such positions in the master time cycle by said impulse generator, said switch having a plurality of contact banks and cooperating energized wipers, and a common driving magnet operated by said generator, for operating said wipers in unison from step to step on said contact banks, each said controller including timing means operating during a part of its cycle to time accord of right of way and cause transfer of right of way from one lane to the next at the end of its timing period, each bank having a plurality of spaced contacts arranged to be successively energized by one of said wipers, and means connecting one of said contacts in each of said banks to a separate one of said controllers to accelerate the respective timing means of the several controllers at predetermined positions of said switch normally to control the relation of such transfers of right of wayby such controllers to the master time cycle.

4. A signalling system including, in combination, a plurality of signallingameans to-be installed:one adjacent each of apluralityofiintersections of traffic lanes and adapted to accord and interrupt right of way in said lanes, a plurality of controllers forsaid intersections and connected each to one of said signalling means to operate the same through a time cycle to transfer right of :way alternatelybetween the intersecting lanes, impulse responsive means individual to each controller and adapted onaccord of right of way to one lane to be operated to cause transfer of right of way to another of the intersecting lanes by said signal and thereby control the time cycle of the signal, a master timing means connected to all of said controllers and comprising a cyclic step by step. rotary switching device for supplyingimpulses to said impulseresponsive means in the several controllersat different predetermined points in its .cycle for determining the time phase relation of .such transfer of right of way by said controllers, said switching device including a plurality of impulse units one for each controller to havea different phase relation with said switching. device, driving means for stepping said switching device and impulse units in unison through such cycle a condenser, power leads and a resistance connected to said condenser to vary its charge overaninterval of time, an electronic :tube 'connectedto said condenser and operable'responsive to a predetermined state of charge onsaid condenser to activate-said driving means, :means acting upon operation of said tube .to reset said condenser charge, and means'for adjusting said resistance to vary said time interval and proportionately vary the time cycle of all said controllers.

5. A signalling system, including ln combination. signalling means-to be :installed adjacent an intersection of trafiic lanesand adapted to accord andinterrupt right of way in said;lane's, a cyclically operating controller for said intersection and connected to said :signalling :means to control the same,.master timing means con nected to said controller to control the .operation thereof, said controller including -a condenser, power leads and a resistance connectible to said condenser to vary the charge on the same over an interval of time, a switchingdevice connected to said signals to operate the same, driving :means for said switching device, an electronic tube connected to said condenser and operable'responsive to a predetermined state of charge .on the same to activate said driving means, and'controlmeans when operable connecting said resistance between said condenser and power leads, and means forming a part of' said master 'timing means to operate periodically said control means.

6. A signalling system, including in combination, signalling means to be installed'at an intersection of trailic lanes and adapted to accordand interrupt right of way in said lanes,.a cyclically operating controller for said intersection and connected to said signalling means to control the same, master timing meansconnected to said controller to control the operation thereof, said controller including a condenser, power leads and a resistance connectible to said condenser to vary the charge on the same over an interval of time, a switching device'connected to said signals to operate the same, drivingmeans forsaid switching device, an electronic tube connected to said condenser and-operableresponsivetoa predetermined-state .of charge on the same to activate said driving means, and control means adapted when'operated in a part of said controller cycle :for connecting said resistance between said. condenser and power leads, and means forming apart of said .master timing meansand connected to said controller to operate periodically said control means, and further means in said controller including a higher resistance and normally connected to said condenser to similarly vary the charge on the same butat a considerably slower rate than said first named chargevarying means such that if said first namedcharge varyingmeans fails to operatezthe slower rate chargingmeans will vary the charge on said condenser to the point where said driving meansis activated.

'7. A signalling system including in combination, signalling means atan intersection of traffic lanes and adapted to accord and interrupt right of way in such lanes, a cyclically operating electrically driven controller for operating the signalling means to transfer right of way between thelanes'periodically at a certain time rat-e, master timing means, a single circuit connecting said master timer to said controller, said master timer operating cyclically totransmit to'said controller electrical impulses'of different values at different times over said circuit, means forming a part of said controller and responsive to only one of said impulses to cause said controller to operate more-rapidly through portions of its cycle, and further means forming a part of said controller and responsive to the other impulse to cause said controller to operate more rapidly through another portion of its cycle.

8. A traffic control system for a plurality of intersections of trafiic lanes, including in combination right of way signalling means at each intersection, traffic actuated means in one of the accorded alternately to the lanes for time periods,

means forming a part of each said controller and connected to be operated by actuations of the traffic actuated means associated therewith to prolong the accordof right of way in the lane of said traific actuated means beyond said time period, means in each said controller to provide when 'operative'a maximum time limit to such prolonged :accordof right of way in such lane, and:a:masteri'timerrconnected to all of said controllerslfor periodically rendering said maximum limit=means operative in the several controllers in .:pre-determined.time relation, whereby if traffic actuation at the respective intersections is su'fiicient'toprolong right of way up to themaximum limitthe periods of accord of right of Way in'the lanes of the'trafiic actuated means will be-maintainedin pre-determined time phase relation at the several intersections.

9. A "traffic control system 'for a plurality of intersections of "traflic-lanes having at each intersecti'on signalling means, traffic actuated means: in the lanes, a controller connected to said actuatedameans and to said signalling means for operating-said signalling means to transfer and accord right of Way'to the lanes alternately for time periods inresponse to actuation of said traffic actuated-means, said time periods being extendable in responseto further actuation in a lane having right of way, maximum timing means comprising: a condenser, means for charging said condenser at a slow rate and means when connected to said condenser responsive to a predetermined charge on said condenser to limit extension of said time periods, and a master timer operating for cyclically connecting said responsive means to said condenser in each controller in a predetermined time relation with the others whereby transfers of right of way occurring by operation of said maximum timing means at all intersections take place in predetermined time relationship.

10. A traffic control system for the intersection of interfering traflic lanes includingsignalling means adapted to accord and interrupt right of way in the lanes, traflic actuated means in the lanes, a controller connected to said signalling means and said traffic actuated means and having alternate signal control positions through which it is adapted to operate to cause said signalling means to accord right of way alternately in the respective lanes in response to actuation of the trafiic actuated means, said controller including a timing device energized in one such alternate position for timing such accord of right of way and prolonging such accord of right of way responsive to actuation of the trafi'ic actuated means during such accord of right of way to the lane of the latter trafiic actuated means, circuit means for operating the controller from such one position to the other to cause the signalling means to interrupt such accord of right of way when the circuit of said circuit means is completed, a second timing device operating at the end of a maximum time period in such one position to prepare said circuit for completion and maintaining said circuit so prepared thereafter while said second timing device remains operated in such one position, and said system including a cyclic master timer for periodically completing said circuit when prepared.

PERCY BAILEY RENSI-IAW. 

